week 9 Flashcards
(38 cards)
time course for non specific LBP – acute vs subacute vs chronic
Acute: < 6 weeks Subacute: 6-12 weeks Chronic: > 12 weeks
why is non specific LBP a term
no pathoanatomical cause to the painw
what % of LBP in primary care settings is non specific
90%
risk factors to non specific LBP
Physical Factors:
Prolonged standing, walking Lifting heavy weights
Unhealthy Lifestyle: Smoking
Obesity
Psychological Factors: Depression
Job dissatisfaction
Prior episode of low back pain
things to rule out via history to diagnose non specific LBP
i.e. red flags like osteoporosis, fractures, cauda equina, neoplasia (cancer), infection, aortic aneurysm
make sure no sensory loss, parenthesis, motor deficits, fever, weight loss, systemic symptoms, bladder and bowel problems, smoking, dyslipidemia, malignancy
neurological exmas
straight leg raise…
check abdominal pain (aortic aneurysm)
LRs of red flags
history of cancer has high LR for spinal malignancy
spinal fracture; prolonged corticosteroid use has LR+ of 48.5 and 3 positive finds of Henschke index (female, >70yrs old, severe trauma, prolonged corticosteroids) has LR+ of 906
C-reactive protein
Acute phase protein which rises in response to inflammation
Non-specific, but can be used together with signs and symptoms and other tests to evaluate for acute or chronic inflammation
Acute=
Any infection, especially bacterial
Acute flares or onset of inflammatory/immune-mediated disease
Chronic=
Chronic infections
Chronic inflammatory/immune-mediated conditions
erythrocyte sedimentation rate
Measurement of the rate at which RBCs settle in saline solution or plasma over a specified time period
Because inflammatory, neoplastic, infectious and necrotic diseases increase the protein content of plasma, RBCs tend to stack upon one another, increasing their weight, causing them to descend faster
Non specific test used to help detect acute and chronic inflammation
Does not change as rapidly as CRP
If elevated usually a result of globulins or fibrinogens
- Polymyalgia rheumatica
-Moderately elevated
Inflammation, anemia, infection, pregnancy
-Very high
Severe infection
imaging for fracture
plain radiograph
imaging for infection, malignancy, neurologic, cauda qeuina
MRI
how long to diagnose non specific LBP
> 6weeks with no identifiable cause is NSLBP.
However, red flags must be ruled out in the
acute presentation and if there is no progress with conservative management
contraindications, advantages and disadvantages of x ray imaging
Contraindications:
pregnancy (relative)
Advantages:
inexpensive, non-invasive, readily available, portable, reproducible, fast, easily read
Disadvantages:
radiation exposure (minimal), generally poor at distinguishing soft tissues
x ray imaging mechanism
Form a short wavelength electromagnetic energy
Photons traverse matter, they can be absorbed (a process known as “attenuation”) and/or scattered
The density of a structure determines its ability to attenuate or “weaken” the x-ray beam
air < fat < water < bone < metal
what to use x ray- plain films for
Structures that have high attenuation (e.g. bone) appear white on the resulting images
x ray plain films vs computed tomography
plain films= 2Dimensional
computed tomogrpahy- anatomic structures are reconstructed
use of x ray- computed tomogrpahy
e.g. CT chest can be viewed using “lung”, “soft tissue”, and “bone” settings)
units for x ray- computed tomography
hounsfiled units
c ray- computed tomography
X-ray beam opposite a detector moves in a continuous 360o arc as patient is advanced through the scanner
Anatomical structures are then reconstructed
x ray= computed tomography AKA
CT scan!!
advantages of CT sc an
biopsies and non invasive and soft tisssue
Delineates soft tissues, excellent at delineating bones and
identifying lung/liver masses May be used to guide biopsies
Spiral/helical multidetector CT has fast data acquisition and allows 3D reconstruction
CTA non-invasive compared to conventional angiography for visualization of vasculature
disadvantages of CT scan
High radiation exposure
Soft tissue characterization is inferior to that seen on MRI Requirement for contrast in some studies (e.g. IV, oral, rectal), Patient anxiety going through scanner
Increased cost and decreased availability compared to plain film Requirement for expert interpretation of images
MRI mechanism
Imaging technique that does not use ionizing radiation and can produce images in virtually any plane
Patient is placed in a magnetic field generated by electric current; protons, typically from water
Molecules, align themselves along the plane of magnetization due to their intrinsic polarity. A pulsed radiofrequency beam is subsequently turned on and deflects all the protons off their aligned axes. When the radiofrequency beam is turned off, the protons return to their pre-excitation axis, giving off the energy they absorbed. This energy is measured with a detector and interpreted by software to generate MR images
what is an MRI signal intensity dependent on
- hydrogen desnity
- magnetic relaxation times (T1 and T2)
what tissues create better signals on MRI
ones with high hydrogen density (i.e. H20)
ones with low hydrogen density i.e. cortical bone and lung are low signal
